Multiple gear pump



Jan. 18, 1955 J. F. MURRAY ETAL 2,699,724

MULTIPLE cm PUMP Filed June 14, 1950 2 Sheets-Sheet J1 .ZE'YVETZfC/TE (Elm F Murray James C. Osborne M 5 7 5-? Jim;

Jan. 18, 1955 J. F. MURRAY ETAL 2,699,724

MULTIPLE GEAR PUMP Fil ed June 14, 1950 2 Sheets-Sheet 2 (/5/72? F 'Murray rfEzmes C. Osborne United States Patent MULTIPLE GEAR PUMP John F. Murray, Macedonia, and James C. Osborne,

Cleveland Heights, Ohio, assignors to Thompson Prodnets, Inc., Cleveland, Ohio, a corporation of Ohio Application June 14, 1950, Serial No. 168,086

4 Claims. (Cl. 103-4) This invention relates generally to fluid displacement apparatus and more particularly to a multiple pumping unit incorporating a plurality of rotary fluid displacement means having pressure loaded pump sealing elements. A particular feature of the present invention includes the provision of frangible couplings between each of the fluid displacement means and a common drive means whereby interrupted operation of one of the pumping units will not interfere with an assured supply of pumping medium.

The structure of the present invention provides a particularly useful application when employed in connection with the supply of a vital fluid to a particularly strategic location, for example, the supply of fuel to the jet engines of a high altitude aircraft. Obviously in such environment interrupted supply of fuel would be critical not only from the point of view of the operator of the aircraft but also with respect to possible damage to or loss of the aircraft itself.

According to the general features of the present invention, a plurality of pressure loaded gear pumps are arranged to be driven in parallel with one another by a common drive means. A frangible coupling is provided between each of the pumping units and the common drive means so that binding or seizure of one of the pumping units will cause a corresponding frangible coupling to break and permit normal uninterrupted operation of the other of the coupling units.

It is an object of the present invention, therefore, to provide a multiple pumping structure wherein continued operation of one of the pumping units will be assured despite the binding and seizure in one of the other pumping units.

A further object of the present invention is to provide a multiple gear pump having a plurality of pumping units to be driven in parallel with one another through a common driving means, each of the pumping units being provided with a frangible coupling yieldable in response to abnormal load conditions.

Another object of the present invention is to provide a pressure loaded gear pump having a plurality of pumping units each discharging into a separate outlet and each having separate communications between a pressure control chamber and a corresponding outlet, each pumping unit being further provided with a frangible coupling to a common driving means so that breakage of one of the couplings will permit uninterrupted operation of the other pumping units.

Many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description which follows and the accompanying sheets of drawings in which a preferred embodiment of the present invention is shown.

On the drawings:

Figure 1 is a rear end elevational view of a multiple gear pump according to the principles of the present invention;

Figure 2 is a transverse cross-sectional view taken substantially along line lI-II of Figures 1 and 3; and

Figure 3 is a cross-sectional view taken substantially along line III-III of Figure 1 and on a larger scale than Figures 1 and 2.

As shown on the drawings: 8 The multiple pump structure of the present inventio is indicated generally by the reference numeral 10 and includes a multi-section housing 11 having a central body 12 with a cover 13 on one end and acap structure 14 2,699,724 Patented Jan. 18, 1955 The various elements of the housing 11 are retained in firm assembly by means of suitable fasteners, for example, the studs and nuts 16.

The body 12 of the housing 11 defines a common fluid inlet passage 17 and the cover 13 and the cap 14 each efines a recess which, together with the side wall portions of the. body 12, form a plurality of pumping chambers 18 and 19, respectively, communicating with the common inlet passage 17 through pumping chamber inlets 20 and 21, respectively.

The pumping chambers 18 and 19 are provided with outlets 22 and 23, respectively, which discharge into an outlet passage 24 formed by an enlarged portion on the cover 13 and an outlet passage 26 formed by an enlarged portion on the body 12.. The outlet passages 24 and 26 merge in a chamber provided by a filter casing portion 25 containing a filter and having a single outlet 25a.

In many respects, each of the pumping units incorporated in the multiple gear pump 10 is of identical construction. Each of the units includes a pair of fixed bushings 2'7-27 having a bearing portion 27a and an end plate portion 27b and being mounted in relatively fixed assembly within the cover 13 and the cap 14.

Rotary fluid displacement means are provided in each of the pumping chambers 18 and'19 and in this embodiment include a pair of intermeshing rotary gears, for example, a pair of driver gears 28-28 and a pair of driven gears 29-29. Each of the gears 28-28 and 29-29 are provided with tubular shafts 30 and 31, respectively, which project outwardly from either side of the gears for journaling purposes. One end of each of the shaft portions 30 and 31 is journaled in a bearing portion 27a of one of the fixed bushings 27.

The other end of each of the shaft portions 38 and 31 is journaled in a bearing portion 33a of one of a pair of slidable bushings 33 located in each of the pumping chambers 18 and 19.

The slidable bushings 33 are each provided with a radially extending end plate portion 3312, the back face of which, together with the walls of the body 12, forming a control pressure chamber 34. Means are provided between each of the pressure chambers 34 and the respective outlets 24 and 26 to introduce pressurized outlet fluid pumped by each of the rotary fluid displacement means so that an axial pressure thrust may be delivered to the slidable bushings 33 to efifect pressure sealed engagement of the end plate portions 33b with the corresponding rotary fluid displacement means.

Because the components of the housing 11 are preferably made out of a light-weight material, such as aluminum or the like, it may be desirable to provide liners 3232 for the pumping chambers 18 and 19 against which the teeth of the gears 28 and 29 may bear. It will be understood that such liners 32--32 may be made of any suitable bearing material and may be placed in the pumping chamber in various ways, for example, the liners mayllae inserted or integrally cast in the cover 13 and the cap As will be noted upon the drawings, the liners 32 do not extend across the entire width of the pumping chamber but terminate short thereof to permit the insertion of a suitable O-ring gasket 36 in encircling relation to each of the end plate portions 33b of the slidable bushing 33 and adjacent the ends of the liners 32. Such arrangement is conveniently provided by forming a suitable counterbore in the locale of each of the pumping chambers in a portion of the body 12.

The body 12 is additionally counterbore as at 12a to receive the end plate portions 33b of the slidable bushings 33, the side wall portions thereof forming the control pressure chambers 34 together with the end plate portions 33b of the bushings 33.

An additional counterbore step 37 is provided in each side of the body 12 to receive an O-ring type gasket 38.

The slidable bushings 33 are normally biased out wardly with respect to the body 12' of the housing it for pressure sealing engagement with the respective rotary fluid displacement means comprising the driver gears 2828 and the driven gears 2929 by suitable resilient members, in the present embodiment taking the form of a coil spring 39 and a coil spring 40, each end of which on the other end.

prime mover (not shown).

The inner end of the stub shaft 42 terminates in a sleeve-like collar 44 having an annular shoulder 45 for cooperation with a shaft sealing structure indicated generally by the reference numeral 46, the details of construction of which not being necessary to the understanding of the principles of the present invention. The shaft sealing structure 46 is retained within appropriately counterbored portions of the cap 14 by means of a cover member or retainer 47 connected to the cap 14 by suitable fasteners 48.

A drive shaft 49 extends completely through one of the tubular shafts 30 with an adequate driving clearance and extends into the other tubular shaft 30.

The extending end of the shaft 49 is splined at 50 into interlocking driving assembly with other tubular shaft 30.

The other end of the shaft 49 is connected to the collar 44 on the end of the stub shaft 42 by a plurality of interlocking splined ribs 51 formed between the end of the shaft 49 and the inside bore of the collar 44.

A plurality of splined ribs 52 are formed between the outside periphery of the tubular shaft portion 30 of one of the driver gears 28 and the bore of the collar 44 near the terminal end thereof. Y

The shaft 49 is provided with a reduced shear neck 53 which, together with the splined ribs 50 interlocked with the mating splined ribs of the driver gear 28, form a frangible coupling for one of the rotary fluid displacement means.

The collar 44 on the end of the stub shaft 42 is provided with a reduced shear neck 54 in approximately the locale between the splined connection of the shaft 49 to the collar 44 and the splined connection of the collar 44 to the tubular shaft 30 of one of the driver gears 28.

The groove 56 provided in one of the tubular shaft portions 30 of one of the driver gears 28 directly adjacent the end of the collar 44 is a conventional machining relief which facilitates cutting of the splines 52.

The reduced shear neck 54, together with the interlocking splined ribs 52, provide a frangible coupling for the other of the rotary fluid displacement means.

The spring 57 is provided between the shaft 49 and the stub shaft 42 in order to maintain the splined rib areas of the collar 44 in correct alignment relative to the tubular shaft portion 30 and the shaft 49.

The provision of the frangible couplings described above provides a very desirable safety feature since bind ing or seizure of one of the pumping units, for example, the unit on the left-hand side of Figure 3, would result in a fracture of the frangible coupling in the locale of the reduced shear neck 53. Since there is adequate running clearance between the shaft 49 and the tubular shaft portion 30 of the driver gear 28 on the other pumping unit, the pumping unit on the right-hand side of Figure 3 would continue to operate.

If, on the other hand, the pumping unit on the righthand side of Figure 3 would be subjected to an abnormal operating condition through binding or seizure, the frangible coupling would fracture in the locale of the reduced shear neck 54. However, the other pumping unit would continue to be driven through the shaft 49.

All broken pieces are readily removed from the pump merely by removing the cover member 46. Further disassembly is not required.

It will be apparent to those versed in the art that various minor modifications may be made to the preferred embodiment herein shown and described in considerable detail for the sake of clarity only; however, it should be clearly understood that we "wish to embrace within the scope of this patent all such modifications as reasonably and properly come within the scope of our contribution to the art.

We claim as our invention:

1. A multiple pump having three longitudinally spaced coaxially aligned rotatable members provided by a stub shaft, a first driver gear inwardly adjacent thereto,

and a second driver gear inwardly adjacent said first driver gear, respectively, a collar connecting said stub shaft and said first driver gear and having a first reduced shear neck formed therein outwardly of its connection to said first driver gear, and a shaft member connected to said second driver gear and extending outwardly through said first driver gear for connection to said tub shaft outwardly of said first shear neck, said shaft member having 10 a second reduced shear neck formed therein adjacent one end thereof outwardly of said first driver gear, and inwardly of the connection of said shaft member to said stub shaft, said first and second shear necks yielding selectively under abnormal load to permit uninterrupted operation of one of said first and second driver gears upon binding of the other, whereby fragments formed upon shearing of said shear necks are positioned outside of said driver gears.

2. A multiple pump comprising a casing having an opening at one end, a cover on said casing for said opening, and at least three longitudinally spaced coaxially aligned rotatable members provided by a stub shaft extending through said cover, a first driver gear inwardly adjacent said stub shaft and a second driver gear inwardly adjacent said first driver gear, respectively, a collar connected to said stub shaft and said first driver gear, said collar having a reduced shear neck formed therein outwardly of its connection to said first driver gear providing a first frangible coupling, said driver gears having bores extending therethrough, and a shaft connected to said second driver gear in the bore thereof and extending outwardly through said bore of first driver gear and being connected to said stub shaft outwardly of said first frangible coupling, said shaft having a reduced shear neck formed therein outside of said bore of said first driver gear to provide a second frangible coupling, said first and second frangible couplings yielding torsionally to permit uninterrupted operation of one of said driver gears upon binding or seizure of the other, 'whereby all fragments formed upon shearing of said frangible couplings are positioned outside of said bores of said driver gears and the broken pieces of said frangible couplings are removable from said casing through said opening.

3. A multiple pump comprising a casing having an opening at one end and being recessed to provide a plurality of longitudinally spaced coaxially aligned pumping cavities inwardly of said opening, first and second rotary gear pumps in said cavities adapted to be operated in tandem, a cover for said opening, a rotatable driver member comprising a stub shaft extending from outside of said casing through said cover and providing an annular collar connected to said first pump, said collar having a reduced shear neck formed therein outside of its connection to said first pump providing a first frangible coupling, and a shaft member connected to said stub shaft and to said second pump, said shaft member having a reduced shear neck formed therein on the side of said first pump nearest the stub shaft, whereby fragments formed upon shearing of said frangible couplings are positioned at one end of the casing, said first and second frangible couplings selectively yielding when a corresponding pump binds or seizes to permit uninterrupted operation of the other pump, the broken pieces being removable through said opening.

4. A pump comprising a casing having an opening at one end and being recessed to provide a plurality of longitudinally spaced coaxially aligned pumping cavities inwardly of said opening, bushing means in each cavity, rotary intermeshing gears in said cavities journalled in said bushing means and including first and second driver gears having longitudinally adjacent bores extending therethrough in register with said opening, a cover for said opening, a rotatable driver member comprising a stub shaft extending from outside of said casing through said cover and providing an annular collar adjacent said first driver member, said collar having a reduced shear neck formed therein and having internal splines formed therein, said first driver gear having an external spline portion connected to said internal splines of said collar with said reduced shear neck between said spline portion of said first driver gear and said stub shaft, and a connecting shaft having splines formed on one end connected to said internal splines of said collar to effect a direct coupling with said stub shaft, said connecting shaft extending through said bore of said first driver gear and having its other end in said bore of said second driver gear, said second driver gear and said connecting shaft having spline connections therebetween, said connecting shaft having a reduced shear neck formed therein inwardly of said splines at said one end outside of said spline portion of said first driver gear, whereby abrasive pieces formed by broken shear necks will be outside said bores of the driver gears and broken pieces of said driver member or said connecting shaft are removable through said opening, said shear necks yielding under abnormal load to permit uninterrupted operation of one driver gear upon binding of the other.

References Cited in the file of this patent UNITED STATES PATENTS 1,218,300 Nelson Mar. 6, 1917 16 Kirkwood Feb. 18, 1902 6 Russel, et a1 May 17, 1927 Grant Apr. 3, 1928 Herman, et a1 Apr. 21, 1942 Johnson Aug. 22, 1944 Miner, Jr., et al Oct. 24, 1944 Etnyre Aug. 14, 1945 Jeannin June 4, 1946 Lauck Dec. 17, 1946 Knudson Nov. 8, 1949 Frei Dec. 13, 1949 Gordinier Feb. 5, 1952 Lauck Jan. 12, 1954 Lauck Jan. 12, 1954 FOREIGN PATENTS Great Britain Aug. 8, 1946 

